Atherosclerosis is a progressive disease of the vascular system whereby atheroma is deposited on the inner walls of blood vessels. Over time atheromatous deposits can become large enough to reduce or occlude blood flow through the vessels, leading to symptoms of low blood flow such as pain in the legs (on walking or at rest), skin ulcer, angina (at rest or exertional), and other symptoms. To treat this disease and improve or resolve these symptoms it is desirable to restore or improve blood flow through the vessel.
Various means are used to restore or improve blood flow through atheromatous vessels. The atheroma deposits can be displaced by diametrically expanding the vessel by inflating balloons, expanding stents, and other methods. However these methods undesirably tear and stretch the vessel, causing scar formation in a high percentage of patients. Such scar tissue (restenotic material), once formed, blocks flow in the vessel and often needs to be removed. The deposits can be pulverized using lasers and other methods. However pulverization alone of atheromatous material allows microemboli to flow downstream and lodge in distal vascular beds, further compromising blood flow to the tissue affected by the disease. Atherectomy catheters can be used to remove atheromatous deposits from the blood vessel and can present an ideal solution when the deposits removed from the vessel are captured and removed from the body. One way to capture and remove such deposits is to store the deposits within the catheter and to subsequently remove the catheter from the body.
One problem that occurs when storing material or deposits in a catheter is that the catheter can have insufficient storage capacity. The portion of the vessel to be treated can be quite extensive. For example, the portion of the vessel to be treated can extend over a vessel length of 200 mm or longer. If the storage chamber in the catheter becomes filled with material the catheter must be removed from the body, the deposits removed from the catheter, and the catheter re-inserted into the body for more deposit removal and storage. However, present methods for removing deposits from catheter collection chambers can be time consuming.
What is needed is a catheter having a simple, fast and effective way of removing deposits from a catheter collection chamber.